Device and method for radio cell selection

ABSTRACT

This disclosure relates to a mobile device, comprising: a receiver configured to receive a radio signal comprising transmissions from a plurality of radio cells; and a processor configured to derive second information from the received radio signal, the second information indicating at least one neighboring radio cell, wherein the processor is configured to initiate a radio cell selection based on the second information if the second information indicates at least one neighboring radio cell configured for the first RAT.

FIELD

The disclosure relates to a mobile device which performs initiating aradio cell selection in a communication network and a method forinitiating a radio cell selection, in particular a self-configured highpriority radio access technology (RAT) search. The disclosure furtherrelates to fallback techniques between different radio accesstechnologies.

BACKGROUND

In current mobile communications 100, e.g. according to the 3GPPstandard, when a mobile device 120 or User Equipment (UE) is in IDLEmode it performs neighboring inter-RAT cell measurement 121, 122, 123and re-selects the best available cell found during the scanning asshown in FIG. 1. Depending on the network, UE 120 obtains an availableinter-RAT (IRAT) neighbor cell list, e.g. including radio cells 111,112, 113, and only the cells from this neighbor cell list are regularlymonitored by the UE 120 to find the best cell for re-selection. Thenetwork usually broadcasts this information on broadcast channels, forexample, in a neighbor cell list indicating radio cells configured forspecific Radio Access Technologies (RAT). It has shown from field trialsthat in most situations such an inter-RAT neighbor cell list is notcorrectly configured. As the UE 120 is completely dependent on thebroadcasted neighbor cell list, even when it is aware of the cells ofthe preferred RAT (for example cell 111 configured for LTE, Long TermEvolution) in its vicinity where it camped previously, it may be stuckin that same low priority RAT (for example a 2G-GSM cell) due to awrongly configured IRAT neighbor cell list. This in turn drasticallyreduces the data throughput performance of a multi-mode LTE capable UEeven though the user is subscribed for LTE data services and a suitableLTE cell is available in its vicinity.

Hence, there is a need to improve the cell search in particular incommunication networks with radio cells configured for different radioaccess technologies.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of embodiments and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments andtogether with the description serve to explain principles ofembodiments. Other embodiments and many of the intended advantages ofembodiments will be readily appreciated as they become better understoodby reference to the following detailed description.

FIG. 1 is a schematic diagram illustrating a communication system 100with a mobile device 120 initiating radio cell selection between radiocells 111, 112, 113 configured for different RATS.

FIG. 2 is a flow chart of an exemplary method 200 for radio cellselection in which a preferred RAT order is LTE-UMTS-GSM and LTEneighboring cells are not configured in 2G-GSM.

FIG. 3 is a flow chart of an exemplary message protocol sequence 300 fora UE with LTE preference camped on GERAN cell.

FIG. 4 is a block diagram of a mobile device 400 according to thedisclosure.

FIG. 5 is a schematic diagram of a method 500 for initiating a radiocell selection according to the disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof, and in which is shownby way of illustration specific aspects in which the invention may bepracticed. It is understood that other aspects may be utilized andstructural or logical changes may be made without departing from thescope of the present invention. The following detailed description,therefore, is not to be taken in a limiting sense, and the scope of thepresent invention is defined by the appended claims.

The following terms, abbreviations and notations will be used herein:

-   RAT: radio access technology,-   IRAT: Inter RAT,-   SI2quarter: 2G system information 2 quarter message,-   UMTS: Universal Mobile Telecommunication System-   GSM: Global System for Mobile Communications-   UTRA: UMTS Terrestrial Radio Access-   EUTRA: evolved UMTS Terrestrial Radio Access-   LTE: Long Term Evolution-   UE: User Equipment, mobile device, cellular handset-   IMS: IP multimedia subsystem-   SRVCC: Single Radio Voice Call Continuity-   CS: circuit switched-   CSFB: circuit switched fallback-   2G/3G/4G: 2^(nd)/3^(rd)/4^(th) Generation-   PLMN: Public Land Mobile Network

It is understood that comments made in connection with a describedmethod may also hold true for a corresponding device configured toperform the method and vice versa. For example, if a specific methodstep is described, a corresponding device may include a unit to performthe described method step, even if such a unit is not explicitlydescribed or illustrated in the figures. Further, it is understood thatthe features of the various exemplary aspects described herein may becombined with each other, unless specifically noted otherwise.

The techniques described herein may be implemented in wirelesscommunication networks, in particular communication networks based onmobile communication standards such as LTE, in particular LTE-A and/orOFDM and successor standards such as 5G. The methods are also applicablefor high speed communication standards from the 802.11 family accordingto the WiFi alliance, e.g. 802.11ad and successor standards. The methodsand devices described below may be implemented in electronic devicessuch as cellular handsets, mobile or wireless devices (or mobilestations or User Equipment (UE)). The described devices may includeintegrated circuits and/or passives and may be manufactured according tovarious technologies. For example, the circuits may be designed as logicintegrated circuits, analog integrated circuits, mixed signal integratedcircuits, optical circuits, memory circuits and/or integrated passives.

In the following, embodiments are described with reference to thedrawings, wherein like reference numerals are generally utilized torefer to like elements throughout. In the following description, forpurposes of explanation, numerous specific details are set forth inorder to provide a thorough understanding of one or more aspects ofembodiments. However, it may be evident to a person skilled in the artthat one or more aspects of the embodiments may be practiced with alesser degree of these specific details. The following description istherefore not to be taken in a limiting sense.

The various aspects summarized may be embodied in various forms. Thefollowing description shows by way of illustration various combinationsand configurations in which the aspects may be practiced. It isunderstood that the described aspects and/or embodiments are merelyexamples, and that other aspects and/or embodiments may be utilized andstructural and functional modifications may be made without departingfrom the scope of the present disclosure.

The basic principle of systems described hereinafter is as follows:Whenever the UE is successfully camped on a suitable cell, it will storethe latest predefined number of cell information along with theirreselection thresholds, priority and PLMN (public land mobile network)values after acquiring these for both serving cell and its neighborcells from their respective system information messages. And upondetecting any of the scenario where the neighbor cell list is notconfigured for high priority RAT, UE will perform self-configuredmeasurements on previously stored cells and may follow the defaultdefined reselection algorithms, e.g. as defined in 3GPP, in particularTS 45.008 (V9.4.0, 2010-10), chapter 6.6.6. Advantages are improved timein the preferred RAT, i.e. a RAT with good throughput, and thus a betteruser experience.

FIG. 2 is a flow chart of an exemplary method 200 for radio cellselection in which a preferred RAT order is LTE-UMTS-GSM and LTEneighboring cells are not configured in 2G-GSM.

When the method 200 is invoked 201, the UE is camped and registered onan LTE cell. EUTRA-AS stores its own reselection thresholds, prioritiesand PLMN information related to serving frequency and neighborfrequencies for high priority search according to block 202. When an IMScall is started (block 203), UE moved to 3G-UMTS cell with SRVCC (SingleRadio Voice Call Continuity) handover (block 204). At next block 205, UEmoved to 2G-GSM cell with CS (circuit-switched) handover. When the callis disconnected, UE moved to IDLE state (block 206). In this IDLE stateUE can perform cell search measurements for which a neighbor cell listis required. Hence, UE checks in block 207 if an LTE neighbor cell list,i.e. a neighbor cell list including cells which are capable of LTE RAT,is broadcast in system information. If such an LTE neighbor cell list isavailable, UE can configure measurement on neighbor cell from systeminformation, i.e. by using this LTE neighbor cell list (see block 209).However, if such an LTE neighbor cell list is not available, UE checksif self-configured high priority RAT search is enabled, i.e. if UEstores its own list from previously camped cells according to theconcept of the disclosure (see block 208).

If self-configured high priority RAT search is enabled, UE can configuremeasurement on neighbor cell from previously camped cell, i.e. from itsown LTE neighbor cell list (see block 210). However, if self-configuredhigh priority RAT search is not enabled, UE will remain in 2G-GSM (block212) if high-priority RAT neighbor cell information not provided inSystem Information Broadcast of service cell. For both cases that aneighbor cell list is available, either broadcast from systeminformation according to block 207 or obtained from self-configurationaccording to block 208, UE performs IDLE mode cell re-selectionprocedure (block 211) before the method 200 ends 213.

The exemplary implementation of FIG. 2 provides a mechanism to return tohigh priority/preferred RAT from a low priority/non-preferred RAT cellwhen such cells are available but the network didn't configure IRATneighbor cells in system information. Currently any such mechanism isnot provided in the 3GPP standards. The scenario in the flowchart ofFIG. 2 shows difference between the UE behavior with and without thedisclosed solution. The flowchart of FIG. 2 explains the exemplaryscenario where the preferred RAT order is LTE-UMTS-GSM and in 2G-GSM,LTE neighboring cells are not configured. The disclosed solution is notlimited to the RAT combination shown in FIG. 2. Any other high priority,i.e. preferred RAT and low priority, i.e. non-preferred RAT may beapplied.

FIG. 3 is a flow chart of an exemplary message protocol sequence 300 fora UE with LTE preference camped on GERAN cell.

Different user equipment entities are shown: A non access stratum (NAS)301, an EUTRA access stratum 302, a UMTS access stratum 303, a GSMaccess stratum 304 and the network (NW) 305.

The non access stratum (NAS) 301 is a 3GPP defined protocol layer thathelps UE to register with Network and access services via multipleavailable access stratum. A non access stratum 301 has interfaces tomultiple access stratum, i.e. to EUTRA access stratum 302, UMTS accessstratum 303, GSM access stratum 304.

In the exemplary implementation of FIG. 3, the UE NAS has access to thenetwork 305 via EUTRA-AS 302 or GSM-AS 304 or via UMTS-AS.

At an initial stage, the UE has access to EUTRA cell via EUTRA-AS 302,where LTE-ERRC radio resource control stores an exemplary number of “n”EUTRA frequency entries with information about thresholds and prioritiesof previously registered cells or neighbor cells (block 306). Dependingon different use cases as described below, the UE may be made to camp ona GERAN cell connecting to the GSM-AS 304. In this GERAN network noEUTRA neighbor cell information is configured in system information,i.e. in SI2quarter information (block 307).

GERAN radio resource (RR) will retrieve the stored EUTRAN frequency listspecific to the camped PLMN, i.e. from the neighbor cell list stored inblock 306 (block 308). Using this stored EUTRAN frequency list, UE willconfigure IRAT measurements on these high priority EUTRA frequencies(block 311). If then an LTE cell is found and the specific reselectioncriteria are met by this LTE cell (block 312), UE can reselect the foundLTE cell (sequence 313) and connect to the EUTRA-AS 302. Otherwise(block 312), UE may stop measuring the stored LTE frequencies and mayre-configure them after a pre-determined periodicity in order to savebattery power (block 314).

As can be seen from the message protocol sequence 300 of FIG. 3, thatrepresents a live network log, a UE with LTE preference (RAT preferenceorder 4G-3G-2G) is reselected from LTE and camped on GERAN cell. But asthat cell has no LTE neighbor cells in broadcast information, the UE isnot able to move back to LTE even when it knows that suitable LTE cellsare available. There are multiple ways how an UE can camp on a GERANcell which is not configured with LTE neighbor cells. The following area few of possible cases.

-   1. UE can be chosen to camp on GERAN cell via cell selection.-   2. UE can be re-selected to GERAN cell via IRAT reselection from    other RATS.-   3. During SRVCC, network may move to a GERAN cell (which does not    have EUTRAN neighbor cells in its SI2Quarter information) by means    of an IRAT handover.-   4. During a CSFB call, network may redirect to a UTRAN cell and    during the CS Call, the UE may move to a GERAN Cell (which does not    have EUTRAN neighbor cells in its SI2Quarter information) by means    of an IRAT handover.-   5. Extended Service Request is sent by UE for a CSFB call and if    network does not provide redirection info in the Connection Release    or T3417ext counter expires then UE may move to such a GERAN cell in    order to perform the CS Call.

When implementing the solution according to this disclosure, aftercamping in such a GERAN cell, UE can retrieve the stored EUTRANfrequencies specific to the camped PLMN and then configure them forperforming EUTRAN IRAT measurements and apply higher priority basedreselection algorithm to reselect to a suitable EUTRAN cell ifavailable.

As UE stores all necessary information including the thresholds andpriority data, UE can only reselect to LTE when the correspondingreselection criteria (e.g. according to 3GPP) is actually met. Hence,such a UE can avoid a Ping-Pong reselection to/from LTE and therebyachieving stability.

Due to mobility when even the stored LTE frequencies do not yield goodmeasurements for reselection, UE can stop configuring these frequenciesfor measurements and may re-configure with a pre-defined periodicity inorder to save battery. The stored list data base can be maintainedacross power cycles, hence even after the next boot up, when UE campedin 2G, the list can be used to reselect to LTE.

FIG. 4 is a block diagram of a mobile device 400 according to thedisclosure.

The mobile device 400 includes a receiver 401, an optional memory 402and a processor 403, e.g. a baseband (BB) processor. The receiver 401 isconfigured to receive a radio signal 408 comprising transmissions from aplurality of radio cells, e.g. transmissions 121, 122, 123 from radiocells 111, 112, 113 as shown in FIG. 1. The optional memory 402 isconfigured to store first information 404 indicating at least oneneighboring radio cell which is configured for a first radio accesstechnology (RAT). Note that the first information does not need to bestored in a memory. The first information can be predetermined, i.e.known by the processor 403. The processor 403 is configured to derivesecond information 405 from the received radio signal 408. The secondinformation 405 indicates at least one neighboring radio cell. Theprocessor 403 is configured to initiate a radio cell selection 407 basedon the second information 405 if 406 the second information 405indicates at least one neighboring radio cell configured for the firstRAT. Alternatively, the processor 403 can initiate the radio cellselection based on the predetermined first information if the secondinformation does not provide information about a neighboring radio cellwhich is configured for the first RAT.

The processor 403 may implement one of the methods 200, 300 describedabove with respect to FIGS. 2 and 3. The first information 404 mayinclude the stored neighbor cell list according to blocks 208, 210 inFIG. 2 or according to block 306 in FIG. 3. The second information 405may include the neighbor cell list received from the system informationcomprised in the received radio signal 408, e.g. according to block 209in FIG. 2 or according to SI2quarter information in blocks 307, 308 inFIG. 3.

The second information 405 may indicate one or more neighboring radiocells which are configured for a second RAT.

The one or more neighboring radio cells which are configured for thefirst RAT may be radio cells according to a first mobile communicationstandard supporting both, the first RAT and the second RAT, e.g. GSM andLTE as described above with respect to FIG. 3.

The one or more neighboring radio cells which are configured for thesecond RAT may be radio cells according to a second mobile communicationstandard which only support the second RAT and not the first RAT, e.g.only GSM and not LTE according to the description with respect to FIG.3.

The one or more neighboring radio cells which are configured for thefirst RAT may be assigned to a first priority. The one or moreneighboring radio cells which are configured for the second RAT may beassigned to a second priority. In one example, the first priority ishigher than the second priority.

The processor 403 may be configured to derive the second information 405from an inter-RAT neighbor cell list comprised in system information ofa broadcast channel of a respective radio cell.

The processor 403 may be configured to update the first information 404stored in the memory 402 based on the second information 405 derivedfrom the received radio signal 408 if the second information 405indicates at least one radio cell which is configured for the first RAT.

The second information 405 may include frequency information, thresholdinformation and priority information of the one or more neighboringradio cells.

The processor 403 may be configured to initiate the radio cell selectionwhen the mobile device is camping on a radio cell which is configuredfor a RAT that is different from the first RAT.

The processor 403 may be configured to initiate the radio cell selectionwhen the mobile device is in an idle mode.

The first information 404 may be stored in a section of the memory whichis maintained across power cycles, i.e. a power-off resistant section ofthe memory.

The processor 403 may be configured to stop initiating the radio cellselection if the radio cell selection based on the first information 404is not enabled and the second information 405 indicates no neighboringradio cell configured for the first RAT, e.g. as described in block 314of FIG. 3.

The processor 403 may be configured to reconfigure the first information404 stored in the memory 402 with the second information 405 which isderived from the received radio signal 408 after a predetermined timeperiod. This may ensure that the first information 404 stored in thememory 402 indicates the latest radio cell environment.

The memory 402 may store a layer 3 protocol stack controlling theprocessor 403 to initiate the radio cell selection.

FIG. 5 is a schematic diagram of a method 500 for initiating a radiocell selection according to the disclosure. The method 500 may forexample be implemented on a processor 403 as described above withrespect to FIG. 4 or on any other computer.

The method 500 includes: receiving 501 a radio signal, e.g. a radiosignal 408 as shown in FIG. 4, comprising transmissions from a pluralityof radio cells, e.g. radio cells 111, 112, 113 as shown in FIG. 1.

The method 500 includes: deriving 502 second information from thereceived radio signal, e.g. second information 405 as described abovewith respect to FIG. 4, the second information indicating at least oneneighboring radio cell.

The method 500 further includes: initiating 503 a radio cell selectionbased on the second information 405 if the second information indicatesat least one radio cell configured for a first radio access technology(RAT), otherwise based on predetermined first information, e.g. firstinformation 404 as described above with respect to FIG. 4, indicating atleast one neighboring radio cell which is configured for the first RAT.

The second information may indicate at least one neighboring radio cellconfigured for a second RAT. The at least one neighboring radio cellwhich is configured for the first RAT may be a radio cell according to afirst mobile communication standard supporting both, the first RAT andthe second RAT.

The at least one neighboring radio cell configured for the second RATmay be a radio cell according to a second mobile communication standardonly supporting the second RAT, i.e. not supporting the first RAT.

The at least one neighboring radio cell which is configured for thefirst RAT may be assigned to a first priority; the at least oneneighboring radio cell configured for the second RAT may be assigned toa second priority, wherein the first priority is higher than the secondpriority.

The method 500 may further comprise: deriving the second informationfrom an inter-RAT neighbor cell list comprised in system information ofa broadcast channel of a respective radio cell. The method 500 mayfurther comprise: updating the first information stored in the memorybased on the second information derived from the received radio signalif the second information indicates at least one radio cell configuredfor the first RAT.

The second information may include frequency information, thresholdinformation and priority information of the at least one neighboringradio cell.

The method 500 may further comprise: initiating the radio cell selectionwhen the mobile device is camping on a radio cell which is configuredfor a RAT different from the first RAT. The method 500 may furthercomprise: initiating the radio cell selection when the mobile device isin an idle mode. The first information may be stored in a section of thememory which is maintained across power cycles.

The method 500 may further comprise: stopping initiating the radio cellselection if the radio cell selection based on the first information isnot enabled and the second information indicates no neighboring radiocell configured for the first RAT, e.g. according to block 314 describedabove with respect to FIG. 3.

The method 500 may further comprise: reconfiguring the first informationstored in the memory with the second information derived from thereceived radio signal after a predetermined time period. The method 500may further comprise: storing a layer 3 protocol stack which isconfigured to control the processor to initiate the radio cellselection.

A method for connecting a mobile device to a radio cell (not depicted)includes: receiving a radio signal comprising transmissions from aplurality of radio cells, e.g. radio cells 111, 112, 113 as describedabove with respect to FIG. 1; connecting the mobile device to a firstradio cell based on predetermined first information indicating at leastone neighboring radio cell which is configured for a first radio accesstechnology (RAT); deriving second information from the received radiosignal, the second information indicating at least one neighboring radiocell; and connecting the mobile device to a second radio cell based onthe second information if the second information indicates at least oneradio cell configured for the first RAT, otherwise based on the firstinformation. The first information may correspond to the firstinformation 404 as described above with respect to FIG. 4. The secondinformation may correspond to the second information 405 as describedabove with respect to FIG. 4.

The method may further include: disconnecting the mobile device from thefirst radio cell before connecting the mobile device to the second radiocell. The first information may be stored in a memory. The secondinformation may indicates at least one neighboring radio cell configuredfor a second RAT. The at least one neighboring radio cell configured forthe first RAT may be a radio cell according to a first mobilecommunication standard supporting both, the first RAT and the secondRAT. The at least one neighboring radio cell configured for the secondRAT may be a radio cell according to a second mobile communicationstandard only supporting the second RAT, e.g. as described above withrespect to FIGS. 3 and 4.

The at least one neighboring radio cell configured for the first RAT maybe assigned to a first priority, and the at least one neighboring radiocell configured for the second RAT may be assigned to a second priority,wherein the first priority is higher than the second priority.

The method may further include: deriving the second information from aninter-RAT neighbor cell list comprised in system information of abroadcast channel of a respective radio cell. The method may furtherinclude: updating the first information stored in the memory based onthe second information derived from the received radio signal if thesecond information indicates at least one radio cell configured for thefirst RAT. The second information may include frequency information,threshold information and priority information of the at least oneneighboring radio cell.

The devices and systems described in this disclosure may be implementedas Digital Signal Processors (DSP), micro-controllers or any otherside-processor or hardware circuit on a chip or an application specificintegrated circuit (ASIC).

Embodiments described in this disclosure can be implemented in digitalelectronic circuitry, or in computer hardware, firmware, software, or incombinations thereof, e.g. in available hardware of mobile devices or innew hardware dedicated for processing the methods described herein.

The present disclosure also supports a computer program productincluding computer executable code or computer executable instructionsthat, when executed, causes at least one computer to execute theperforming and computing blocks described herein, in particular themethods 200, 300, 500 described above with respect to FIGS. 2, 3 and 5and the computing blocks described above with respect to FIG. 4. Such acomputer program product may include a non-transient readable storagemedium storing program code thereon for use by a processor, the programcode comprising instructions for performing the methods or the computingblocks as described above.

EXAMPLES

The following examples pertain to further embodiments. Example 1 is amobile device, comprising: a receiver configured to receive a radiosignal comprising transmissions from a plurality of radio cells; and aprocessor configured to derive second information from the receivedradio signal, the second information indicating at least one neighboringradio cell, wherein the processor is configured to initiate a radio cellselection based on the second information if the second informationindicates at least one neighboring radio cell configured for a firstradio access technology (RAT).

In Example 2, the subject matter of Example 1 can optionally includethat the processor is configured to initiate the radio cell selectionbased on predetermined first information if the second information doesnot provide information about a neighboring radio cell which isconfigured for the first RAT.

In Example 3, the subject matter of Example 2 can optionally includethat the second information indicates at least one neighboring radiocell configured for a second RAT.

In Example 4, the subject matter of Example 3 can optionally includethat the at least one neighboring radio cell configured for the firstRAT is a radio cell according to a first mobile communication standardsupporting both, the first RAT and the second RAT.

In Example 5, the subject matter of any one of Examples 3-4 canoptionally include that the at least one neighboring radio cellconfigured for the second RAT is a radio cell according to a secondmobile communication standard only supporting the second RAT.

In Example 6, the subject matter of any one of Examples 3-5 canoptionally include that the at least one neighboring radio cellconfigured for the first RAT is assigned to a first priority, whereinthe at least one neighboring radio cell configured for the second RAT isassigned to a second priority, wherein the first priority is higher thanthe second priority.

In Example 7, the subject matter of any one of Examples 1-5 canoptionally include that the processor is configured to derive the secondinformation from an inter-RAT neighbor cell list comprised in systeminformation of a broadcast channel of a respective radio cell.

In Example 8, the subject matter of any one of Examples 2-7 canoptionally include that the processor is configured to update the firstinformation based on the second information derived from the receivedradio signal if the second information indicates at least one radio cellconfigured for the first RAT.

In Example 9, the subject matter of any one of Examples 1-8 canoptionally include that the second information comprises frequencyinformation, threshold information and priority information of the atleast one neighboring radio cell.

In Example 10, the subject matter of any one of Examples 1-9 canoptionally include that the processor is configured to initiate theradio cell selection when the mobile device is camping on a radio cellwhich is configured for a RAT different from the first RAT.

In Example 11, the subject matter of any one of Examples 1-10 canoptionally include that the first information is stored in a memorysection which is maintained across power cycles.

In Example 12, the subject matter of any one of Examples 1-11 canoptionally include that the processor is configured to stop initiatingthe radio cell selection if the radio cell selection based on the firstinformation is not enabled and the second information indicates noneighboring radio cell configured for the first RAT.

In Example 13, the subject matter of Example 12 can optionally includethat the processor is configured to reconfigure the first informationwith the second information derived from the received radio signal aftera predetermined time period.

In Example 14, the subject matter of any one of Examples 1-13 canoptionally include a layer 3 protocol stack controlling the processor toinitiate the radio cell selection.

Example 15 is a method for initiating a radio cell selection, the methodcomprising: receiving a radio signal comprising transmissions from aplurality of radio cells; deriving second information from the receivedradio signal, the second information indicating at least one neighboringradio cell; and initiating a radio cell selection based on the secondinformation if the second information indicates at least one radio cellconfigured for a first radio access technology (RAT), otherwise based onpredetermined first information indicating at least one neighboringradio cell which is configured for the first RAT.

In Example 16, the subject matter of Example 15 can optionally includethat the second information indicates at least one neighboring radiocell configured for a second RAT.

In Example 17, the subject matter of Example 16 can optionally includethat the at least one neighboring radio cell configured for the firstRAT is a radio cell according to a first mobile communication standardsupporting both, the first RAT and the second RAT.

In Example 18, the subject matter of any one of Examples 16-17 canoptionally include that the at least one neighboring radio cellconfigured for the second RAT is a radio cell according to a secondmobile communication standard only supporting the second RAT.

In Example 19, the subject matter of any one of Examples 16-18 canoptionally include that the at least one neighboring radio cellconfigured for the first RAT is assigned to a first priority, whereinthe at least one neighboring radio cell configured for the second RAT isassigned to a second priority, wherein the first priority is higher thanthe second priority.

In Example 20, the subject matter of any one of Examples 15-19 canoptionally include: deriving the second information from an inter-RATneighbor cell list comprised in system information of a broadcastchannel of a respective radio cell.

In Example 21, the subject matter of any one of Examples 15-20 canoptionally include: updating the first information based on the secondinformation derived from the received radio signal if the secondinformation indicates at least one radio cell configured for the firstRAT.

In Example 22, the subject matter of any one of Examples 15-21 canoptionally include that the second information comprises frequencyinformation, threshold information and priority information of the atleast one neighboring radio cell.

In Example 23, the subject matter of any one of Examples 15-22 canoptionally include: initiating the radio cell selection when the mobiledevice is camping on a radio cell which is configured for a RATdifferent from the first RAT.

In Example 24, the subject matter of any one of Examples 15-23 canoptionally include: initiating the radio cell selection when the mobiledevice is in an idle mode.

In Example 25, the subject matter of any one of Examples 15-24 canoptionally include that the first information is stored in a memorysection which is maintained across power cycles.

In Example 26, the subject matter of any one of Examples 15-25 canoptionally include: stopping initiating the radio cell selection if theradio cell selection based on the first information is not enabled andthe second information indicates no neighboring radio cell configuredfor the first RAT.

In Example 27, the subject matter of Example 26 can optionally include:reconfiguring the first information with the second information derivedfrom the received radio signal after a predetermined time period.

In Example 28, the subject matter of any one of Examples 15-27 canoptionally include: storing a layer 3 protocol stack which is configuredto control the processor to initiate the radio cell selection.

Example 29 is a method for connecting a mobile device to a radio cell,the method comprising: receiving a radio signal comprising transmissionsfrom a plurality of radio cells; connecting the mobile device to a firstradio cell based on predetermined first information indicating at leastone neighboring radio cell which is configured for a first radio accesstechnology (RAT); deriving second information from the received radiosignal, the second information indicating at least one neighboring radiocell; and connecting the mobile device to a second radio cell based onthe second information if the second information indicates at least oneradio cell configured for the first RAT, otherwise based on the firstinformation.

In Example 30, the subject matter of Example 29 can optionally include:disconnecting the mobile device from the first radio cell beforeconnecting the mobile device to the second radio cell.

In Example 31, the subject matter of any one of Examples 29-30 canoptionally include that the first information is stored in a memory.

In Example 32, the subject matter of any one of Examples 29-31 canoptionally include that the second information indicates at least oneneighboring radio cell configured for a second RAT.

In Example 33, the subject matter of Example 32 can optionally includethat the at least one neighboring radio cell configured for the firstRAT is a radio cell according to a first mobile communication standardsupporting both, the first RAT and the second RAT.

In Example 34, the subject matter of any one of Examples 32-33 canoptionally include that the at least one neighboring radio cellconfigured for the second RAT is a radio cell according to a secondmobile communication standard only supporting the second RAT.

In Example 35, the subject matter of any one of Examples 32-34 canoptionally include that the at least one neighboring radio cellconfigured for the first RAT is assigned to a first priority, whereinthe at least one neighboring radio cell configured for the second RAT isassigned to a second priority, wherein the first priority is higher thanthe second priority.

In Example 36, the subject matter of any one of Examples 29-35 canoptionally include: deriving the second information from an inter-RATneighbor cell list comprised in system information of a broadcastchannel of a respective radio cell.

In Example 37, the subject matter of any one of Examples 29-36 canoptionally include: updating the first information based on the secondinformation derived from the received radio signal if the secondinformation indicates at least one radio cell configured for the firstRAT.

In Example 38, the subject matter of any one of Examples 29-37 canoptionally include that the second information comprises frequencyinformation, threshold information and priority information of the atleast one neighboring radio cell.

Example 39 is a device for initiating a radio cell selection, the devicecomprising: means for receiving a radio signal comprising transmissionsfrom a plurality of radio cells; means for deriving second informationfrom the received radio signal, the second information indicating atleast one neighboring radio cell; and means for initiating a radio cellselection based on the second information if the second informationindicates at least one radio cell configured for a first radio accesstechnology (RAT), otherwise based on predetermined first informationindicating at least one neighboring radio cell which is configured forthe first RAT.

In Example 40, the subject matter of Example 39 can optionally includethat the second information indicates at least one neighboring radiocell configured for a second RAT.

Example 41 is a communication system, comprising: a receiver componentconfigured to: receive a radio signal comprising transmissions from aplurality of radio cells; a connection component configured to connectto a first radio cell based on predetermined first informationindicating at least one neighboring radio cell which is configured for afirst radio access technology (RAT); and a processing componentconfigured to derive second information from the received radio signal,the second information indicating at least one neighboring radio cell,wherein the connection component is configured to connect to a secondradio cell based on the second information if the second informationindicates at least one radio cell configured for the first RAT,otherwise based on the first information.

In Example 42, the subject matter of Example 41 can optionally includethat the first information is stored in a memory section which ismaintained across power cycles.

In Example 43, the subject matter of any one of Examples 41-42 canoptionally include that the second information indicates at least oneneighboring radio cell configured for a second RAT.

Example 44 is a computer readable non-transitory medium on whichcomputer instructions are stored which when executed by a computer causethe computer to perform the method of any one of Examples 15 to 38.

In addition, while a particular feature or aspect of the disclosure mayhave been disclosed with respect to only one of several implementations,such feature or aspect may be combined with one or more other featuresor aspects of the other implementations as may be desired andadvantageous for any given or particular application. Furthermore, tothe extent that the terms “include”, “have”, “with”, or other variantsthereof are used in either the detailed description or the claims, suchterms are intended to be inclusive in a manner similar to the term“comprise”. Furthermore, it is understood that aspects of the disclosuremay be implemented in discrete circuits, partially integrated circuitsor fully integrated circuits or programming means. Also, the terms“exemplary”, “for example” and “e.g.” are merely meant as an example,rather than the best or optimal.

Although specific aspects have been illustrated and described herein, itwill be appreciated by those of ordinary skill in the art that a varietyof alternate and/or equivalent implementations may be substituted forthe specific aspects shown and described without departing from thescope of the present disclosure. This application is intended to coverany adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in aparticular sequence with corresponding labeling, unless the claimrecitations otherwise imply a particular sequence for implementing someor all of those elements, those elements are not necessarily intended tobe limited to being implemented in that particular sequence.

The invention claimed is:
 1. A device, comprising: a receiver configuredto receive a radio signal comprising transmissions from a plurality ofradio cells; and a processor configured to determine, from the receivedradio signal, second information indicating at least one neighboringradio cell, and to initiate a radio cell selection (i) based on thesecond information when the second information indicates at least oneneighboring radio cell configured for a first radio access technology(RAT), or (ii) based on first information in an absence of the secondinformation indicating a neighboring radio cell that is configured forthe first RAT.
 2. The device of claim 1, wherein the first informationis predetermined.
 3. The device of claim 1, wherein the secondinformation indicates at least one neighboring radio cell configured fora second RAT.
 4. The device of claim 3, wherein the at least oneneighboring radio cell configured for the first RAT is a radio cellaccording to a first mobile communication standard supporting the firstRAT and the second RAT.
 5. The device of claim 3, wherein the at leastone neighboring radio cell configured for the second RAT is a radio cellaccording to a second mobile communication standard supporting thesecond RAT.
 6. The device of claim 3, wherein: the at least oneneighboring radio cell configured for the first RAT is assigned a firstpriority, the at least one neighboring radio cell configured for thesecond RAT is assigned to a second priority, and the first priority ishigher than the second priority.
 7. The device of claim 1, wherein theprocessor is configured to determine the second information from aninter-RAT neighbor cell list included as part of system information of abroadcast channel of a respective radio cell.
 8. The device of claim 1,wherein the processor is configured to update the first informationbased on the second information determined from the received radiosignal when the second information indicates at least one radio cellconfigured for the first RAT.
 9. The device of claim 1, wherein thesecond information comprises frequency information, thresholdinformation, and priority information of the at least one neighboringradio cell.
 10. The device of claim 1, wherein the processor isconfigured to initiate the radio cell selection when the mobile deviceis camping on a radio cell that is configured for a RAT different fromthe first RAT.
 11. The device of claim 1, wherein the first informationis stored in a memory and is maintained across power cycles of thedevice.
 12. The device of claim 1, wherein the processor is configuredto stop initiating the radio cell selection when the radio cellselection based on the first information is not enabled and the secondinformation indicates no neighboring radio cell configured for the firstRAT.
 13. The device of claim 12, wherein the processor is configured toreconfigure the first information with the second information determinedfrom the received radio signal after a predetermined time period. 14.The device of claim 1, wherein the processor is controlled via a layer 3protocol stack to initiate the radio cell selection.
 15. A method forinitiating a radio cell selection, comprising: receiving a radio signalcomprising transmissions from a plurality of radio cells; determining,from the received radio signal, second information indicating at leastone neighboring radio cell; and initiating a radio cell selection (i)based on the second information when the second information indicates atleast one neighboring radio cell configured for a first radio accesstechnology (RAT), or (ii) based on first information in an absence ofthe second information indicating a neighboring radio cell that isconfigured for the first RAT.
 16. The method of claim 15, wherein thesecond information indicates at least one neighboring radio cellconfigured for a second RAT.
 17. The method of claim 16, wherein the atleast one neighboring radio cell configured for the first RAT is a radiocell according to a first mobile communication standard supporting thefirst RAT and the second RAT.
 18. The method of claim 16, wherein the atleast one neighboring radio cell configured for the second RAT is aradio cell according to a second mobile communication standardsupporting the second RAT.
 19. The method of claim 16, wherein: the atleast one neighboring radio cell configured for the first RAT isassigned a first priority, the at least one neighboring radio cellconfigured for the second RAT is assigned a second priority, and thefirst priority is higher than the second priority.
 20. The method ofclaim 15, wherein the act of determining the second information includesdetermining the second information from an inter-RAT neighbor cell listincluded as part of system information of a broadcast channel of arespective radio cell.
 21. The method of claim 15, further comprising:updating the first information based on the second informationdetermined from the received radio signal when the second informationindicates at least one radio cell configured for the first RAT.
 22. Amethod for connecting a mobile device to a radio cell, the methodcomprising: receiving a radio signal comprising transmissions from aplurality of radio cells; connecting the mobile device to a first radiocell based on first information indicating at least one neighboringradio cell that is configured for a first radio access technology (RAT);determining, from the received radio signal, second informationindicating at least one neighboring radio cell; and connecting themobile device to a second radio cell (i) based on the second informationwhen the second information indicates at least one neighboring radiocell configured for a first radio access technology (RAT), or (ii) basedon the first information in an absence of the second informationindicating a neighboring radio cell that is configured for the firstRAT.
 23. The method of claim 22, further comprising: disconnecting themobile device from the first radio cell before connecting the mobiledevice to the second radio cell.
 24. The method of claim 22, wherein thefirst information is stored in a memory.
 25. The method of claim 22,wherein the second information indicates at least one neighboring radiocell configured for a second RAT.